The present invention relates to a control apparatus and a method of controlling a position of a hanging flexible covering such as a blind.
Various arrangements for controlling flexible coverings such as blinds exist. A common arrangement includes a torsion spring that is fitted within a rotatable cylinder around which the blind material is wound. As the blind is unfurled, the torsion spring is turned, creating a reverse direction force that is intended to compensate for the weight of the curtain material hanging from the cylinder. However, in practice, the use of a torsion spring and the necessary gearing required to maintain a desired blind position is often problematic. The force applied by the torsion spring is only in balance with the force resulting from the weight of the hanging portion of the blind for a relatively small range of the travel of the blind between its fully wound and fully unwound positions. Thus, the effort required by a user to fully wind/unwind the blind can be substantial, especially when larger blinds are used. Alternatives to this type of torsion spring mechanism have been tried, e.g. electric motors, but these tend to be expensive and/or complex.
Embodiments of the present invention are intended to address at least some of the problems associated with such conventional arrangements.